Multirotor gas turbine power plant with propeller



Aug. 9, 1949. A. H. REDDING 2,47%206 UULTIROTOR GAS TURBINE POWER PLANT WITH PROPELJER l Filed Feb. 24. 1944 3 Sheets-Sheet 1 lNvENToR AFWG@ 2 2.

wnNEssEs:

ARNoLn. H. REDDING Aug.. 9, 1949. A. vl-l. REDDING I 2,473,206

MLTIROTOR GAS TURBINE PWER PLANT WITH PROPELLER Filed Feb. 24. 1944 -3 Sheets-Sheet 2 INVENToR ARNoLn HREDmNa.

ATTORNEY Aug. 9,1949.- A. H. Rl-:DplNG l 2,478,206

lULnnoTon @As TURBINE Pom PLANT una rnoPnLLER FiledFeb. 24.. 1944- 3 Sheets-Sheet 3 wlTNEssEs: F'g Q 5 INVENToR ARNOLD H Rename.

ma.. i BY OVSPaRM;

ATTORNEY Patented Aug. 9, 1949 MULTIROTOR GAS TURBINE POWER PLANT WITH PROPELLER Arnold H. Redding, Swarthmore, Pa., assig'nor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvaniav Application February 24, 1944, Serial No. 523,715

( Cl. .6D-35.6)

8 Claims.

This invention relates to power plants for aircraft and particularly to a plant comprising a gas turbine having several independent and oppositely rotating rotors and it has for an object to provide an improved device of the character set forth.

While not limited thereto the present invention is particularly applicable to gas turbine power plants such as used for the propulsion of aircraft. When so used one or morey airplane propellers as well as a compressor which compresses the motive iiuid for the turbine are directly driven by a respective rotor of the turbine. The blading of the rotors is arranged to apportion the power extracted by each rotor in a predetermined ratio.

Ordinarily, large amounts of power cannot be extracted eciently from a small number of stages of a turbine Where the peripheral velocities of the rotors are low; however, by having a high peripheral speed rotor follow one or more low speed rotors, and especially when they rotate in opposite directions, it is possible to extract large amounts of power in the low-speed rotor or rotors and use the large tangential velocities, which would otherwise be wasted, in the high speed rotor.

This arrangement is used to advantage in the present invention in that it permits airplane propellers to be directly connected to the low speed rotors and an eiidcient high-speed compressor to be directly connected to the high-speed rotor.

The thrust oi the propellers driving the airplane is augmented by discharging the motive uid, leaving the multi-rotor turbine, as a jet through a nozzle and thereby further increasing the overall emciency ci the power plant.

It has been proposed to propel aircraft at extremely high speeds by the employment of a jet motor in which air is compressed and heated by combustion of fuel supported by the compressed air. The resulting motive fluid comprising the products oi combustion and the excess compressed air is discharged through a propulsion nozzle as a jet, the reaction of which serves to drive the aircraft at a high rate ci speed. It has also been proposed to compress the air by means of a compressor driven by a turbine rotor disposed in the path of the motive iiuid and which extracts a portion of the energy in the motive fluid. While plants of the type mentioned are capable of propelling aircraft at high speeds, their rate of fuel consumption is extremely high and their thermal emciency is good only when operating at maximum thrust. The result is that aircraft powered by plants of this type have a very short cruising 2 range as compared Ito aircraft driven by internal combustion engine driven propellers.

It is an object of the present invention to improve the eiiiciency of a gas turbine power plant and increase the cruising range of the aircraft by employing a multi-rotor turbine which in addition to extracting power from the hot motive fluid for driving the air compressor also extracts power from the motive iiuid for driving the propellers of the airplane.

It is also an object of the present invention to employ axially-aligned oppositely rotating propellers operating in a duct and at speeds substantially greater than speeds at which propellers of comparable power now in common use operate.

These and other objects are elected by the invention as will be apparent from the following description and claims taken in connection with the accompanying drawing, forming a part of this application, in which:

Fig. l is a diagrammatic plan View of an airplane in which two power plants made in accordance with the. present invention have been mounted, one of the ducts surrounding the airplane propellers being broken away;

Fig. 2 is an enlarged side elevational View of one of the plants shown in Fig. i, the wing and duct surrounding the propellers being broken away for the sake of clarity;

Fig. 3 is an enlarged vertical sectional view` the rear portion of the plant shown in Figs, and 2;

Fig. 4 is a vector diagram illustrating the turbine blade and motive fluid velocities; and

Figj is a developed plan view taken substantially on the line V-V of Fig. 3.

The airplane, generally indicated It, shown diagrammatically in Fig. l may be of conventional design including a fuselage l i, tail structure i 2 and a Wing i3. In the embodiment shown, two power plants it, made vin accordance with the present invention, are mounted in the Wing of the of l.

' airplane. The power plants are preferably of the open duct type and extend into the wing from the trailing edge with the inlet of each communicating with a tunnel or duct i5 formed in the wing and which opens to the leading edge of the wing, for admitting air to the plants.

The power plants It are identical and a description of one will suiiice. Each plant comprises in general an outer shell or casing structure I6 open from end to end and a central core structure il providing an annular flow passage I8 extending fore and aft with respect to the airplane.

The central core structure l'lY is supported by the casing structure along its longitudinal axis and includes a front fairing cone I9 in which fuel and lubricating oil pumps and ignition apparatus (not shown) may be supported. The core structure also includes a'rotor 2| of an axial flow cornpressor 22, rotors 23, 24 and 25 of a turbine, generally indicated 26, and a conical tail piece 21 which defines with the rear or outlet end of the casing an annular propulsion nozzle 28. An annular combustion chamber 29 is mounted within the casing between the compressor and the turbine for heating the compressed air before it enters the turbine.

The present invention is not concerned with the specific design of the compressor and combustion apparatus although a preferred form of compressor is shown in my copending application Serial No. 503,930, led September 27, 1943, now Patent No. 2,446,552, and preferred combustion apparatus is shown in the copending application of Stewart Way et al., Serial No. 511,468, flied November 23, 1943, each application being assigned to the assignee of the present invention. A In general, the power plant operates as follows: Air enters the compressor 22 through the duct I5 and is compressed. On leaving the compressor, the air enters an annular diffuser passage 3l which effects a further compression of the air. rIhe air then passes through numerous openings 32 provided in the annular combustion chamber which is of conical or triangular section, as shown in Fig. 3. In this chamber, the compressed air is mixed with fuel supplied under pressure to a row of atomizing nozzles 33 providing continuous combustion' after being ignited by any suitable means such as one or more spark plugs 34. The hot motive fluid, comprising the products of combustion and excess air heated by the combustion, on leaving the combustion chamber is directed by nozzle forming guide varies 35 into the divergent' blade passage of the multi-rotation turbine 2E. The spent gases leaving the turbine are discharged through the propulsion nozzle 28 at a high velocity so that the energy remaining in the motive fluid is used to propel the aircraft.

The tailpiece 21 of the propulsion nozzle may, if desired, be made longitudinally movable with respect to the outer casing as shown for example in the patent of Donald Bradbury, No. 2,402,363,

granted June 18, 1946, tothe assignee of the present invention, to increase or decrease the flow area o'f the propulsion nozzle and thereby vary the jet effect and to change the back pressure of the turbine.

The turbine 26 comprises two low speed rotors 23 and 24 which are adapted to rotate in'opposite directions and at substantially the same speed and a high speed rotor 25. Although not limited thereto, in the particular embodiment shown, the low speed rotors 23 and 24 may rotate at about 1800 R.. P. M. and the high speed rotor 25 may rotate at about 13,000 R. P. M. at maximum thrust.

The low speed rotors 23 and 24 are supported by means of suitable bearings 31 on an inner tubular Wall structure 38 carried by the outer casing structure I6 and defining therewith an intermediate portion of the flow passage I8. The high speed rotor 25 is connected by a shaft 39 to the rotor 2| of compressor 22. The shaft 39 is journaled in suitable bearings shown diagrammatically at 4I and 42, which may be carried by the inner wall structure 38. d

The low speed rotor 23 carries two rows of blades 23a and 23h. The row of blades 23a is provided with ashroud ring 43, to which is secured a plurality of forwardly extending relatively thin flexible metal strips 44 which are closely spaced and disposed outside of a Wall 45 of the casing structure I6. The free ends of the strips 44 are secured to one flange of an annular rigid ring 45 preferably of channel section, forming the hub of a propeller 41.

The propeller 41 may comprise any desired number of blades 48 of airfoil section, as shown in Fig.2, and it is preferred that the propeller have a solidity of the order of 25% or more so that it will handle full power, as at takeoff, without stalling. v

Suitable known sealing means may be employed throughout the turbine, as between the strips 44 and the Wall 45 to prevent leakage of motive fluid.

from the turbine 26 to the atmosphere.

The low speed rotor 24 is driven by three rows of blades identified 24a, 24h and 24e. The central row of blades 24h have their roots secured to the rotor in any suitable manner while their tips are secured to a shroud ring 49. The shroud ring 49 has secured thereto a plurality of closely spaced flexible stripsy 50, similar to the strips 44. The forward ends of the strips 50 are in turn secured to a flange 5I of a hub 52 of a second propeller 53 comprising airfoil blades 54. The blades 48 and 54 of the propellers'41 and 53, respectively, are of opposite pitch and rotated in opposite directions by the oppositely rotating rotors 23 and 24.

The first row of blades 24a of the rotor 24 is disposed between the blades 23a and 23h and is carried by a shroud ring 55 which is secured to the free end of the strips 50 and the hub flange 5I. The third row of blades 24e of the rotor 24 are carried by a shroud ring 56 which is in turn secured to a flange 51 of the rear propeller hub 52.

By employing laterally flexible strips 44 and 50 for connecting the propeller hubs 46 and 52 to the rotors 23 and 24, respectively, each row of turbine blades is free to expand or contract due to temperature changes without stressing the propeller structure while at the same time providing a structurally rigid assembly.

The high speed rotor 25 carries two rows of blades 25a and 25h and this rotor rotates in a direction opposite to that of the rotor 24 with the row of blades 25a disposed between the row of blades 24h and 24c of the low speed rotor 24.

In the particular embodiment shown, the propellers 41 and 53 have an over-all diameter, from tip to tip of diametrically opposed blades, of about 8 feet and are designed to rotate at about 1800 R. P. M. which is substantially greater than the conventional airplane propeller. The propeller blades 48 and 54 are of airfoil section and operate efficiently at this high speed within a duct ring 59 of streamline cross section, as shown in Fig. 3. The duct ring 59 is supported from the wing I3 by suitable brackets 6I extending rearwardly from the trailing edge of the airplane wing.

` The portion of the casing I6 extending rearwardly from the propeller hub 52 may be secured to and rotate with this hub, suitable struts 62 being provided for supporting the tailpiece 21 from this portion of the casing. The struts 62 are of streamlined section and disposed at a suitable angle to the direction of flow through the propulsion nozzle so that they offer a minimum of resistance to the flow.

The' turbine blading is designed so that the compressor is driven at a much higher speed than the propellers, that a balanced torque relation is maintained, and that the work outputs for the blade rows are of the same order as the heat drops thereover. The balanced torque relation is secured by having torques of the nozzles and the blades 24a, 24D and 24e in balanced relation with respect to the blades 23a, 23h, and 25a and 25h.

In Fig. 4, there is shown a velocity vector diagram together with a diagrammatic illustration showing a preferred shape and angular disposition ofa pair of` blades of each blade row of the turbine. The motive fluid leaving the combustion chamber and entering the nozzles formed by guide vanes 35 is represented by vector lit and i`"s shown as substantially axial of the turbine in direction. The motive fluid is turned by the` guide vanes 35 so that it -has velocity in direction and amount, on leaving the nozzles, represented by the vector t5. The vector 58 represents the velocity of the nrst row of moving blades 23a so that the relative velocity of the motive fluid entering the blades tta is represented by the vector l?.

rihe motive fluid in flowing through the passages between the blades ita is turned by these blades so that it has a velocity, leaving and relative to these blades, represented by the vector t8. The velocity of the motive iiuid at this instant, relative 4to the second row of blades 2da of the rotor it, which rotates in a direction opposite to the rotor E25, is represented by the vector te since the velocities of the rotors 23 and 2li are additive as represented by the vector il.

As the motive fluid passages through the blade row dirait is turned so that its leaving velocity is represented by the vector l2. yThe velocity of the motive duid relative to the third row of blades Nb is represented by the vector 'lt since again the velocities of the rows i3d and 23h are additive as represented by the vector it.

The velocity of the :motive fluid in passing through the succeeding stages of the turbine is .determined in a manner similar to that described above s'o that the motive iluid in passing through the third row of blades 25h is turned and its leaving velocity is represented by the vector l5, resulting in a velocity represented by the vector i8 relative tothe succeeding stage itl. The vector il represents the combined velocities of the blade rows i3?) and Ztl).

The motive fluid entering the blade row Zlib has a velocity represented by the vector it and is turned in passing through this stage so that it has a leaving velocity represented by the vecn tor it. The velocity of the motive uid relative to thesucceeding high speed blade row 25a is represented by the vector ld, the vector 8l representing the sum of the velocities of the low speed blade row ith and the high speed blade row 25a.

In passing through the high speed blade row 25a the motive fluid is turned so that its velocity on leaving this row s represented by the vector B2 and its velocity relative to the succeeding low speed blade row Mc is represented by the vector 83 since the velocities of the blade row 25a and 2te are added as represented by the vector 84 since the adjacent blade rows rotate in opposite directions.

in passing through the low speed blade row 24e the motive :duid is turned so that its velocity on leaving and relative to this row is represented by the vector 85, the velocity relative to the nal blade row 25h being represented by the vector 86.

The vector 81 represents the combined velocities of the blade rows Maand 25h.

In passing through the nal blade row 25h the motive fluid is turned so that its relative velocity on leaving this row is` represented by the vector 88. The' vector 89 represents the blade velocity of the final blade row 25h so that the velocity of the motive uid leaving the inal row and relative to the casing I6 is represented by the vector 9|, which, it will be noted is axial or nearly so with the result there is substantially no swirling loss in the motive fluid on leaving the nal blade row.

It is desirable that the motive fluid be discharged from the propulsion nozzle 28 substantially axial and this condition is obtained as evidenced by the vector diagram and particularly -the direction of the vector 9i which represents the velocity of the motive uid leaving the turbine 26.

,While the invention has been shown in but one form, it willbe obvious to those skilled in the are that it is not so limited, but is susceptible of various changes and modiiications Without departing from the. spirit thereof, and it is desired, therefore, that only such limitations shall be placed thereupon-as are specifically set forth in the appended claims.

What is claimed is:

1. .A gas turbine power plant comprising a casing structure, a core structure mounted coaxially within said casing structure and dening therewith an annular ow passage, said core structure including an axial flow compressor rotor, blading in said passage carried by said casing structure and said rotor, said core structure also including a plurality of turbine rotors downstream of said compressor rotor, blading in said passage and carried by said turbine rotors, with the blading of the respective rotors arranged so that said rotors rotate in opposite directions, means in said passage for heating the compressed air flowing from said compressor to said turbine blades, a propeller concentric with and axially overlapping one of said tur-bine rotors, means connecting said propeller to the tips of the blades of said one turbine rotor, and means connecting the other of said turbine rotors rotor.

2. A gas turbine power plant comprising a casin-g structure, a core structure mounted coaxially within said casing structure and dening therewith an annular ilow passage, said core structure including an axial flow compressor rotor', blading in said passage carried by said casing structure and said rotor, said core structure also including a plurality of turbine rotors downstream of said compressor rotor, blading in said passage and carried by said turbine rotors, with the 'blading of 'the respective rotors arranged so that said rotors rotate in opposite directions, means in said passage for heating the compressed air flowing from said compressor to said turbine blades, a propeller concentric with said turbine rotors, means connecting said propeller to the tips of the blades of one of said turbine rotors, and means connecting the other said turbine rotors to said compressor rotor, the said means connecting the propeller and the tips of the blades being arranged to permit expansion and contraction of said blades.

3. A gas turbine power plant comprising a casto said compressor ing structure, a core structure mounted coaxially ture including an axial flow compressor rotor,

`propeller concentric with said turbine rotors,

means connecting said propeller to the tips of the blades of one of said turbine rotors, and means connecting the other said turbine rotors to said compressor rotor, the rotor connected to the lpropeller being adapted to rotate at a lower speed than the other rotor and said other rotor being disposed downstream of the rst mentioned rotor.

4. A gas turbine powervplant comprising a casing structure, a core structure mounted coaxially within said casing structure and dening therewith an annular iiow passage, said core structure including an axial flow compressor rotor, blading in said passage carried by said casing structure and said rotor for effecting compression of air, means located downstreams of said blading adapted to heat the air compressed by said compressor, and a turbine disposed downstream or said air heating means, said turbine comprising at least three rotors arranged so that adjacent rotors turn in opposite directions, blading carried by the respective turbine rotors and disposed in said passage, the blading of the respective turbine rotors being arranged so that the turbine rotor` at the downstream end of the turbine rotates at a substantially greater speed than the upstream rotors, means connecting said downstream turbine rotor to the compressor rotor for driving the same, a pair of propellers arranged to rotate in opposite directions and substantially concentric with said turbine rotors,-means for connecting a propeller of the pair to a respective upstream turbine rotor, said last-mentioned means including flexible means connecting said propellers to the periphery of their respective turbine rotors. i

5. A power plant of the character set forth in claim 4 and further including an annular duct concentric to said propellers. Y

6. A power plant comprising a compressor; a multi-rotor turbine adapted to be driven by fluid compressed by said compressor, said turbine having at least three rotors arranged so that adjacent rotors turn in opposite directions; combustion apparatus adapted to heat the fluid compressed by said compressor prior to its passage through said turbine; a pair of propeller hubs arranged con-centric with said turbine rotors; means flexiibly connecting the hub of each of said propellers with a respective turbine rotor; and means for transmitting the power developed in the third turbine rotor to the compressor.

7. A power plant comprising a casing structure, a core structure mounted coaxially within said casing structure andy defining therewith an annular flow passage, said core structure including an axial ow compressor rotor, blading in said passage carried by said casing structure and said rotor, said core structure also including l'a plurality of rotors. down stream of said compressor rotor, a combustion chamber disposed in the flow path of air from said compressor rotor to said plurality of rotors, `blading in said passage and carried by said rotors, at least one of said rotors being adapted to rotate at a speed substantially greater than the other rotor or rotors, means connecting said high speed rotor to said compressor for driving the same, and a propeller carried by and adapted to rotate with one of said low speed rotors, said propeller extending radially outwardly of said casing.

8. In an axial-flow turbine, a stator structure provided with an axially-extending tubular element, first, second and third rotors arranged coaxially with respect to the tubular element with the second rotor extending between the first and third rotors; bearings for supporting the rst and second rotors on the tubular element for rotation about the latter; means for supporting the third rotor including a shaft member extending through the tubular element; interleaving rows of blades carried by the rotors and arranged to provide-for l'rotation of the second rotor oppositely to the rst and third rotors; a plurality of nozzles carried by the stator structure for supplying elastic fluid for i'low through the blade passages of the rows of blades; a pair of driven devices disposed in encompassing relation with respect to the blading; and means utilizing the blading for connecting the driven devices to the rst and second rotors.

ARNOLD H. REDDING.

REFERENCES CITED UNITED STATES PATENTS Number Name Date 760,037 Stumpf May 17, 1904 864,400 Wing Aug. 27, 1907 906,133 Hedlund Dec. 8, 1908 910,036 Wolfson Jan. 19, 1909 996,324 De Ferranti June 27, 1911 1,017,564 vLake Feb. 13, 1912 1,055,308 Benjamins Mar. 11, 1913 '1,056,288 MacIntosh Mar. 18, 1913 2,168,726 Whittle Aug. 8, 1939 2,292,288 Pateras Pescara Aug. 4, 1942 2,404,767 Heppner July 23. 1946 2,409,446 Pavlecka et al Oct. 15, 1946 FOREIGN PATENTS- Number Country Date 50,224 Denmark Apr. 29, 1935 OTHER REFERENCES Ser. No. 367,666, Anxionnaz et al. (A. P. C.), pub. May 25, 1943.

Flight, issue of May 13, 1943, pp. 496-498.

Flight, issue of Feb. 17, 1944, page 171. 

